Our laboratory is focused on the study of renal potassium channels, a diverse group of integral membrane proteins that facilitate the passive (driven by the electrochemical gradient for K) movement of K across the cell membranes. This work has led to the discovery of two novel K channel genes, KCNA10 (Shaker-related, voltage-gated K channel), KCNK1 (a two-pore channel) and to a gain-of-function mutation in the voltage-gated Shaker K channel, KCNA3. KCNA10, the subject of the present proposal, encodes a voltage-gated, cyclic nucleotide regulated, K-selective channel expressed in kidney, heart and blood vessels. Our main goals are to determine its molecular structure and establish its role in kidney. Preliminary studies suggest that KCNA10 is a heteromultimeric complex as evidenced by the identification of three proteins that interact with KCNA10 and modify its kinetic properties and expression level. We propose to investigate the molecular mechanisms underlying these interactions. In addition, we plan to determine the kinetic properties and renal expression of a KCNA10 splice isoform we recently identified. KCNA10 protein was detected at the luminal membrane of rat proximal tubule by immunocytochemistry using a polyclonal antibody generated in rabbit. Western blotting also confirmed KCNA10 protein expression in rat cortical membrane. Based on the foregoing we hypothesize KCNA10 is a heteromultimeric, voltage-gated, apical K channel that modulates proximal tubular membrane potential. We therefore, propose to confirm the expression of KCNA10 at the apical membrane of proximal tubules using patch clamp.A knockout mouse model for KCNA10 will be generated and characterized fully, with particular attention paid to its role on proximal tubular function. These studies should provide important information regarding the molecular structure of KCNA10 and its role in renal solute homeostasis.